Kidney Week 2014: Renal Biopsy – Clinical Correlations

Renal Biopsy: Clinical Correlations (Saturday, November 15, 2014, 4:30-6:30 pm).
Moderators: Ingeborg Bajema and Michael Mengel
Clinical Discussant: Liz Lightstone

Case #1:
Sharan Singh presented a 65 year old woman with recurrent uritcaria, angioedema, irritable bowel syndrome, and hematuria. The clinical differential diagnosis included systemic lupus erythematosus, Henoch Schonlein purpura, and small vessel vasculitis. Laboratory studies showed low C3, undetectable C4, elevated Rheumatoid factor, anti-Ro (SSA) as well as anti-SSB antibodies. No anti-neutrophil cytoplasmic antibodies, lupus anticoagulant or antiphospholipid antibodies were detectable. Renal biopsy showed an endocapillary proliferative glomerulonephritis with cryoglobulin deposits and small vessel vasculitis. A diagnosis of hypocomplementemic urticarial vasculitis syndrome was made. Confirmation was obtained by demonstrating anti-C1q antibodies. The patient responded well to Rituximab therapy. The possibility of a monoclonal gammapathy with antibodies to C1q esterase inhibitor was not excluded. Hepatitis C virus test was negative but other viral infections were not worked up.

Case #2:
Kerstin Amann presented a 30 year old woman with nephrotic range proteinuria and hematuria. While light microscopy and immunofluorescence findings suggested a diagnosis of membranous nephropathy, electron microscopy revealed 10-30 nm fibrils characteristic of fibrillary glomerulonephritis. This condition is often idiopathic, although some cases are associated with hepatitis, lupus erythematosus and other systemic conditions. The entity needs to be distinguished from immunotactoid glomerulopathy, where the fibrils are wider and have a microtubular architecture, and patients have to be worked up for an underlying lymphoproliferative disease or monoclonal gammapathy.

Case #3:
Mark Haas presented a case with a history of cerebrovascular accident, hemolytic anemia, elevation in serum creatinine, urine protein/creatinine ratio of 1.8 and pyuria . The clinical differential diagnosis included thrombotic microangiopathy, bacterial endocarditis, sarcoidosis, tuberculosis, Waldenstrom’s macroglobulinemia, and a paraneoplastic glomerulonephritis. The biopsy showed a large B-cell lymphoma with and intraglomerular component that explained the proteinuria, and an interstitial component that accounted for the pyuria. The patient was treated with Rituximab.

Case #4:
Samih Nasr presented a 66 year old woman with diabetes mellitus, retinopathy, and nephrotic syndrome with a bland urine sediment. The clinical diagnosis as well as initial pathology impression was one of diabetic nephropathy. However, the mesangial nodules were focally PAS negative and not argyrophilic. Similar material was seen in an interstitial location in the cortex but not in the medulla. Congo red established a diagnosis of amyloidosis superimposed on diabetic changes. Mass spectrometry showed that that the amyloid was of the ALECT2 variety. This is now the 3rd most common renal amyloid at the Mayo Clinic, and must be particularly suspected in patients of Hispanic, Native American, Middle eastern or South East Asian origin.

Case 5:
Terence Cook presented a 67 year old man with a recurrent melanoma on his leg. He was on simvastatin, lansoprazole, Nivolumab and Ipilimumab. A rising serum creatinine raised the possibility of a drug induced reaction or a paraneoplastic syndrome but a renal biopsy showed metastatic melanoma.

Post by Dr. Parmjeet Randhawa, eAJKD Contributor. 

Check out more of eAJKD’s coverage of Kidney Week 2014! Also, follow @eAJKD on Twitter for live updates!

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